Tracking iron oxide nanoparticles in plant organs using magnetic measurements

Common bean plants were grown in soil and irrigated with water solutions containing different concentrations of $$\hbox{Fe}_3\hbox{O}_4$$ nanoparticles (NPs) with a mean diameter close to 10 nm. No toxicity on plant growth has been detected as a consequence of Fe deficiency or excess in leaves. In order to track the $$\hbox{Fe}_3\hbox{O}_4$$ NPs, magnetization measurements were performed in soils and in three different dried organs of the plants: roots, stems, and leaves. Some magnetic features of both temperature and magnetic field dependence of magnetization M(T, H) arising from $$\hbox{Fe}_3\hbox{O}_4$$ NPs were identified in all the three organs of the plants. Based on the results of saturation magnetization $$M_\mathrm{s}$$ at 300 K, the estimated number of $$\hbox{Fe}_3\hbox{O}_4$$ NPs was found to increase from 2 to 3 times in leaves of common bean plants irrigated with solutions containing magnetic material. The combined results indicated that M(T, H) measurements, conducted in a wide range of temperature and applied magnetic fields up to 70 kOe, constitute a useful tool through which the uptake, translocation, and accumulation of magnetic nanoparticles by plant organs may be monitored and tracked.